1. Field of the Invention
The present invention relates to an electric field emission display (FED), and more particularly, to an FED having a spacer for maintaining a predetermined distance between an anode and a cathode, obtained by stacking a multitude of insulating materials and electrode material, and to a method of manufacturing a spacer of the FED.
2. Description of the Related Art
An electric field emission display (FED) which is a flat panel display, uses a phenomenon in which electrons emitted from an electron gun of each of pixels collide against a fluorescent material due to a strong electrical field formed between an anode and a cathode to emit light beams from the fluorescent material. The FED has a large merit, compared to a cathode ray tube (CRT). That is, the FED has a wide viewing angle, excellent resolution, a low driving voltage, and stability with respect to temperature. Thus, the FED which is currently used for military applications or a view finder for a video camera is expected to be used in car navigation systems, notebook computers, and high definition televisions (HDTV).
FIG. 1 is a sectional view of a conventional field emission display (FED).
Referring to FIG. 1, in the conventional FED 10, indium tin oxide (ITO) glass plates 11 and 12 are provided in upper and lower portions, and a frit glass (not shown) is provided at the sidewall. Also, the inside of the upper ITO glass plate 11 has an anode (not shown) obtained by patterning the ITO glass to have a predetermined form, and red (R), green (G), and blue (B) fluorescent materials 14 are coated on the anode. Also, the upper surface of the lower ITO glass plate 12 includes a cathode line 15 formed by patterning the ITO glass to have a predetermined form, and a Mo tip 16 for emitting electrons and a gate 17 for applying a constant voltage to emit electrons are alternately arranged on the cathode line 15.
The conventional FED must operate in a high vacuum state to increase mean free path of electrons emitted from the Mo tip 16. However, an increase in the area of the screen causes a warping of the screen in high vacuum conditions, so that spacers must be provided. Thus, an individual spacer is bonded between the upper ITO glass plate 11 and the lower ITO glass plate 12, thereby increasing the manufacturing cost of the spacers, and the bonding process is difficult. Also, the conventional FED uses the Mo tip 16, so that the electron emission efficiency is deteriorated due to oxidation of the Mo tip 16 during frit glass firing at a high temperature. Also, a SiO.sub.2 layer having a thickness of 1 .mu.m is used between the gate 17 and the cathode line 15, so that leakage current is generated when a high voltage is applied. Also, the conventional FED employs a vaporable getter tube to obtain high vacuum, so that the volume of the display device is increased. More electrodes emitted from the Mo tip 16 become spread, to thereby generate cross-talk, and lower the luminance of the fluorescent material 14.
Meanwhile, FIG. 2 is a sectional view showing the structure of another conventional FED.
Referring to FIG. 2, the above FED has a structure similar to that of the FED of FIG. 1. However, spacers are provided between the field emission arrays. That is, the spacer 23 between an anode plate 21 of the FED 20 and a cathode plate 22 is provided, thereby the anode plate 21 and the cathode plate 22 are supported spaced a predetermined distance. Also, an anode 21a and a cathode 22a are provided on the anode plate 21 and the cathode plate 22, respectively, and a multitude of microtips 24 spaced a predetermined distance apart from each other are formed on the cathode plate 22. The microtips 24 are provided in the passing hole 26 surrounded by the insulating layer 25 formed on the cathode plate 22. Also, the gates 27 are stacked on the insulating layer 25. R, G, and B fluorescent materials 28 are coated on the anode 21a. Here, the spacer 23 functions as a support maintaining the interval between the anode plate 21 and the cathode plate 22. The spacer 23 is formed by screen-printing a glass paste several times using a mask 29, as shown in FIG. 3.
However, in the method of manufacturing a spacer using the above conventional screen printing method, processes of screen printing and curing are repeated approximately seven times, such that the height of the spacer 23 which becomes an interval between the anode plate 21 and the cathode plate 22 is 200 .mu.m. Thus, much time is required, the glass paste flows down during curing, or it is difficult to increase the aspect ratio of the height vs the occupying width of the spacer 23 in the surface of the supported object, 23 due to misalignment during the repeated process.
Also, the spacer 23 formed of glass having insulation does not have electrical repelling force with respect to electrons. Thus, the electrons emitted from the microtips 24 are partially absorbed into the spacer 23 while proceeding toward the anode 21a, and thus the number of electrons colliding against the fluorescent material 28 of the surface of the anode 21a is reduced, to thereby deteriorate the luminance.